1. Field of the Invention
The present invention relates to a resin composition comprising a polymer and a solvent. The resin composition of the invention can be formulated into a coating for a substrate to impart a stain resistance to the coated surface.
2. Description of the Prior Art
In the past, a coating material for forming a protective layer on a substrate was normally required to be conveniently applied to the surface of the substrate and adhered to the surface permanently so as to obtain an aesthetic appearance. A coating material had not been strictly required to exhibit stain resistant properties. However, there are materials existing in our living environment which will contaminate a coating layer, damage the appearance of the coated surface, deprive the coated surface of protection properties, and shorten the duration time of the coating.
It is conventional to apply an acrylic resin coating, an alkyd resin coating, a novolak resin coating, an amino resin coating, or an epoxy resin coating to the surface of a substrate. Although the resin coatings may meet short-term requirements, due to the poor structural morphology, low surface hardness, and high surface energy of the resins per se, the resin coatings would not be able to provide the coated surfaces with satisfactory stain resistant properties. Since coatings that satisfy consumers' needs should possess highly stain resistant properties, in coating industry, there is a continuous need for a coating material exhibiting satisfactory stain resistant performance.
JP 6-345823 discloses a fluorine-containing copolymer resin which may provide good weathering resistance and water repellence after a long-term outdoor exposure. The copolymer is obtained by polymerizing a hydroxy-containing acrylate monomer, a fluoroolefin monomer and a perfluorovinyl monomer. The resultant resin is cured by a non-yellowing isocyanate curing agent at room temperature to form a coating. Upon a six-month outdoor exposure, the coating still keeps the original surface gloss and water repellence.
JP 7-026204 discloses a fluorine-containing polyurethane polymer. The polymer is prepared from the polymerization of a polyol which has an unsaturated group in the molecule and has an average molecular weight of from 300 to 3,000 and perfluoro acrylic acid or a perfluorovinyl monomer. The resultant resin is cured by an isocyanate ester at room temperature to form a coating. Upon a 2000-hour exposure in an expedited weathering tester, the coating retains more than 88% of the original surface gloss, higher than the 70% surface gloss of the fluoroolefin-vinyl ether polymer coating produced by Asahi Glass Fluoropolymers Co., Ltd. The organic fluoro polymer coating of JP 7-026204 is resistant to weathering, corrosion, and chemicals.
Although the above-mentioned prior art techniques may resolve the problem associated with the staining of coatings resulted from some staining materials, it is still necessary to seek for other coating materials exhibiting stain resistance against other staining sources.
Moreover, there are prior art techniques that incorporate a long fluoro side-chain into a resin and provide the resin with —OH radicals so as to impart reactivity to the product. However, in view of the difference in the polarities of the monomers, there would exist phase separation in the resultant resins which would result in the breaks of the coating film and the reduction of the stain resistance of the coating film.